This invention relates to compositions for the care of contact lenses and methods employing such compositions.
A care regimen for contact lenses involves various functions, such as regularly cleaning the lens with a contact lens solution containing a surface active agent. Rinsing of the contact lens is generally required following cleaning to remove loosened debris. Additionally, the regimen may include treatment to disinfect the lens, treatment to render the lens surface more wettable prior to insertion in the eye, or treatment to condition (e.g., lubricate or cushion) the lens surface so that the lens is more comfortable in the eye. As a further example, a contact lens wearer may need to rewet the lens during wear by administering directly in the eye a solution commonly referred to as rewetting drops.
Separate solutions may be designed for the individual segments of the care regimen. For convenience purposes, multipurpose contact lens solutions have gained popularity, i.e., solutions which can be used for several segments of the care regimen.
Multipurpose contact lens solutions which effectively clean the contact lens, and can also be used to treat the lens immediately prior to insertion of the lens in the eye, represent the more difficult multipurpose solutions to develop. Conventional surface active agents used as primary cleaning agents in the cleaning segment of the regimen, as well as various other components such as antimicrobial agents included as a preservative or disinfectant, tend to be irritating to the eye. Additionally, the surface active agents must not inhibit the wetting or conditioning function of the solution.
A principal component of the compositions of this invention is a silicone polymer containing an alkyleneoxide side chain.
U.S. Pat. No. 4,613,380 (Chen) reports tests evaluating the effectiveness of various agents for removing lipid deposits from silicone elastomer contact lenses. A silicone polymer containing an alkyleneoxy side chain (Dow Corning.RTM. 190), designated in the patent as "Surfactant 1", was employed as a comparative example in tests for effectiveness at removing lipid deposits from the contact lenses.
U.S. Pat. Nos. 4,048,122 and 4,126,587 (Sibley et al.) describe compositions for cleaning soft and silicone contact lenses which contain a polyoxyalkylene modified silicone resin and at least one fatty acid amide or nitrogen analog thereof. Although a broad class of modified silicone resins are mentioned, the described silicone resins are preferably block copolymers having the formula: EQU TSi(O(SiMe.sub.2 O).sub.x (C.sub.n H.sub.2n O).sub.y T'.sub.3
wherein T is alkyl of from 1 to 3 carbon atoms, usually methyl, T' is alkyl of from 1 to 6 carbon atoms, usually 3 to 4 carbon atoms, n is an integer of from 2 to 30, and x and y are numbers within various ranges.
It will be appreciated that the silicone resin in the Chen patent was reported as not particularly effective as a primary cleaning agent for contact lens deposits. Additionally, neither the Chen patent nor the Sibley patents suggests that the compositions can wet or condition a contact lens, or that the compositions are sufficiently nonirritating for in-eye use.